Coil handling magnet



Jan. 18, 1966 J. TRIMBLE 3,230,425

COIL HANDLING MAGNET Filed Sept. 28, 1962 INVENTOR. JAMES TRIMBLE,

ATTORNEYS.

United States Patent Ohio Filed Sept. 28, 1962, Ser. No. 226,954 4 Claims. (Cl. 317-159) This invention relates to an electro-magnet for lifting annular bodies, and has particular utility in the lifting and handling of coiled steel strip and the like.

The use of electro-magnets for handling iron and steel or other magnetic materials is, of course, old and well known. It is also conventional to modify the shape of magnets used for lifting unusually shaped objects, the general goal being to provide as large a contact area as is possible.

It has been found particularly desirable to utilize electro-magnets for the lifting and handling of coiled strip steel and the like during the course of its production. This is primarily because it is extremely difficult to handle such coils by means of conventional lifting methods. However, electro-magnets presently utilized for this purpose have certain drawbacks. It will of course be understood that it is very important in handling such coils that they be maintained in a centered and balanced position with respect to the lifting means. If this balance is not maintained, the coil, when lifted. will tend to tilt; and when the coil is set down, the outer laps will be damaged. This problem is particularly acute in the use of the bulls eye magnet which is one of the most common designs in use today. Such a magnet has one pole in the center, and the other pole on the periphery of the lifting face. Due to well known principles of magnetics, the center pole will not align itself over the hole in the coil. That is, the magnet will prefer to have the central pole on one side of the coil and the peripheral pole on the opposite side of the coil. This makes it very difficult to maintain the coil in a vertical position when lifted.

It is therefore a primary object of this invention to provide an improved coil handling magnet which will secure the coil in a centered and balanced position so that it may be readily moved about in a vertical position without damage.

Another object of this invention is the provision of such a magnet which while accomplishing the aforemen tioned purpose, comprises a very small number of parts and can be readily manufactured and assembled.

Various other objects will become apparent to one skilled in the art upon reading this specification and eX- amining the accompanying drawings, in which:

FIG. 1 is a bottom plan view of a magnet according to the instant invention; and

FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1.

Referring now specifically to FIG. 2, it will be seen that the magnet frame of this invention comprises a horizontally disposed center portion 1 and a pair of downwardly projecting pole .members 2 and 3. In the embodiment shown in the drawings, these members are shown as three separate pieces secured together by a plurality of long bolt-s 4 extending through the magnet. If desired, it would of course be possible to construct the magnet frame from a one-piece casting. In any event, it is to be preferred that the pole members 2a and 3a are nearly identical in size and that they be of mutually opposed substantially half round configuration in bottom plan view as shown in FIG. 1.

The center portion 1 serves as a core for the magnet windings shown generally at 5. These windings are entirely conventional, and may be adapted to suit the requirements of any given operation. Preferably, the Wind- 3,230,425 Patented Jan. 18, 1966 ings 5 are enclosed by a top plate 6, secured to the pole members 2 and 3 by any conventional means, such as the bolts 7, and by similar side plates which are not shown in the figures. It will be understood that these plates should be non-magnetic to prevent short circuiting the magnetic flux.

To provide a means for mechanically assisting the centering of the magnet over the coil to be lifted, a nonmagnetic cone 8 is provided between the pole members 2 and 3. It will be noted that the conical member 8 is mounted on a rectangular base plate 9, which is secured by means of the bolts 10 to the lower inside edges of the pole members 2 and 3. The plate 9 should also be constructed from non-magnetic material.

Directing attention now to FIG. 1 of the drawings which is a bottom view of a magnet formed according to this invention, the contacting faces 2a and 3a of the pole members 2 and 3 respectively, are clearly illustrated. It is to be preferred that the distance A be equal to the diameter of the largest coils to be handled by the magnet. And similarly, the distance B should be equal or somewhat less than the inside diameter of the coils to be handled. It will now be apparent that the diameter of the cone 8 at its largest point is very slightly smaller than the inside diameter of the coil to be lifted. Therefore, as the unenergized magnet is set down on top of a coil, the cone 8 will serve to mechanically center the entire magnet with respect to the coil.

The windings 5 previously described are connected to a suitable supply of electric current by means of the leads 14. When the power is turned on, the pole members 2 and 3 will have opposite polarities, and there will be no tendency for the magnet to move itself out of alignment.

A lifting bridle must be provided for attaching the magnet of this invention to a crane or other hoist. The bridle shown schematically in FIG. 2 comprises a pair of lugs 11 formed on the pole members 2 and 3. Short chains 12 are suitably secured to the suspension lugs 11, and are both joined to a common hoisting ring 13. It is to be preferred that the bridle should be either non-magnetic gr insulated so that it will not short circuit the magnetic While this invention has been described and illustrated by means of a concrete embodiment, it will be understood that numerous modifications may be made 'without departing from its spirit and scope. What is claimed as new and what is desired to be secured by Letters Patient is:

1. An electro-magnet for lifting annular bodies comprising a horseshoe shaped magnet frame having a pair of downwardly projecting pole members, said pole members being of equal size'and of mutually opposed substantially half round configuration in horizontal cross section, one of said pole members being of positive polar-ity and the remaining pole member being of negative polarity, and a non-magnetic cone shaped member mounted on said frame intermediate said pole members and extending downwardly therebeyond for centering said electro-magnet with respect to said annular body to be lifted.

2. An electro-magnet for lifting annular bodies comprising a magnet frame having a horizontally disposed portion and a pair of spaced apart downwardly projecting pole members adapted to be placed at diametrically opposed points on said annular body being lifted, an electrical winding surrounding said horizontally disposed portion of said frame, means to supply electric current to said winding whereby one of said pole members is of positive polarity and the remaining pole member is of negative polarity, and a non-magnetic cone shaped member secured at its base to said frame intermediate said pole members, the tip of said cone shaped member extending downwardly beyond the ends of said pole members.

3. An electro-magnet for lifting annular bodies having a predetermined inside diameter comprising a magnet frame having a horizontally disposed portion and a pair of spaced apart downwardly projecting pole members, an electrical winding surrounding said horizontally disposed portion of said frame, means to supply electric current to said winding, whereby one of said pole members is of positive polarity and the remaining pole member is of negative polarity, and a non-magnetic cone shaped member secured at its base to said frame intermediate said pole members, the base of said cone shaped member having a diameter closely approaching the inside diameter of said body to be lifted, the tip of said cone shaped member extending downwardly beyond the ends of said pole members whereby when said electro-magnet is placed over an annular body without supplying current to said winding, said cone shaped member will serve to center said electro-magnet with respect to said annular body whereby References Cited by the Examiner UNITED STATES PATENTS 966,855 8/1910 Phillips 317164 2,946,616 7/1960 Carter 29465.5 3,015,045 12/1961 Ward 317164 3,139,563 6/1964 Freeman 317-164 BERNARD A. GILHEANY, Primary Examiner.

JOHN F.- BURNS, Examiner. 

1. AN ELECTRO-MAGNET FOR LIFTING ANNULAR BODIES COMPRISING A HORSESHOE SHAPED MAGNET FRAME HAVING A PAIR OF DOWNWARDLY PROJECTING POLE MEMBERS, SAID POLE MEMBERS BEING OF EQUAL SIZE AND OF MUTUALLY OPPOSED SUBSTANTIALLY HALF ROUND CONFIGURATION IN HORIZONTAL CROSSSECTION, ONE OF SAID POLE MEMBERS BEING OF POSITIVE POLARITY AND THE REMAINING POLE MEMBER BEING OF NEGATIVE POLARITY, AND A NON-MAGNETIC CONE SHAPED MEMBER MOUNTED ON SAID FRAME INTERMEDIATE SAID POLE MEMBERS AND EXTENDING DOWNWARDLY THEREBEYOND FOR CENTERING SAID ELECTRO-MAGNET WITH RESPECT TO SAID ANNULAR BODY TO BE LIFTED. 